Fuel Cells Chemistry Notes
Fuel Cells :
→ These are like that of primary cells. In this cell; combustion of fuel takes place and chemical energy produced from it is converted into electric energy. These cells are made in such a way that fuel could be filled continuously in them and so the electric curerent is obtained continuously.
→ In this cell, H2,CO,CH4 C3H8, C2H5OH etc., are used as fuel. First of all, Bacon formed a cell in which he has taken H2 O2 as fuel. It is called Bacon cell. This cell contains porous electrodes of carbon which are impregnated by Pt. Ag or CuO etc.
→ Here, electrolyte is filled between electrodes. Electrolyte is KOH or NaOH solution. H2 and O2 gases are passed in electrolytic solution through porous electrodes.
Reactions take place as follow at electrodes :
- Anode : 2H2(g) + 4OH–(aq) → 4H2O(l) + 4e–
- Cathode : O2(g) + 2H2O(l) + 4e– → 40H–(aq)
- Net Reaction : 2H2(g) + O2(g) → 2H2O(aq)
Since, fuel is consumed during reaction. So, it should be filled again and again.
Characteristics of Fuel Cells –
- Electric current is continuously produced by the fuel continuously.
- These cells are eco-friendly.
- Their efficiency is high which is approximate to 75-80%.
Note The fuel cell is first used to provide electric energy to Appolo shuttle in space programme. Here, Hy and O2 react to form liquid H2O. Condensed form of this water vapour is used as drinking water for space passengers.